isa boiler control system fundamentals
TRANSCRIPT
© 2003, ISAES15w (1.0)
ISA Seminars on the Web
Live Experts on Hot Topics
© 2003ISA67 Alexander DriveResearch Triangle Park, NC 27709
© 2003ISA67 Alexander DriveResearch Triangle Park, NC 27709 Version 1.0
ES15w
Introduction toBoiler ControlSystems
© 2003, ISAES15w (1.0)
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Seminar Logistics
• Seminar materials− Downloadable presentation
− Question and Answer session (audio and email)
− Survey
− Earn 1 Professional Development Hour (PDH)
• Seminar length− 60 minute presentation
− Three 10-minute question and answer sessions
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Audio Instructions
• As a participant, you are in a “listen-only”mode.
• You may ask questions via the internet, usingyour keyboard, at any time during thepresentation. However, the presenter maydecide to wait to answer your question untilthe next Q&A Session.
• If you have audio difficulties, press *0.
• If you have visual difficulties, call (866) 493-2825.
© 2003, ISAES15w (1.0)
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Audio Instructions
• As a participant, you are in a “listen-only”mode.
• You may ask questions via the internet, usingyour keyboard, at any time during thepresentation. However, the presenter maydecide to wait to answer your question untilthe next Q&A Session.
• If you have audio difficulties, press *0.
• If you have visual difficulties, call (866) 493-2825.
6
Audio Instructions
• As a participant, you are in a “listen-only”mode.
• You may ask questions via the internet, usingyour keyboard, at any time during thepresentation. However, the presenter maydecide to wait to answer your question untilthe next Q&A Session.
• If you have audio difficulties, press *0.
• If you have visual difficulties, call (866) 493-2825.
© 2003, ISAES15w (1.0)
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Audio Instructions for Q&A Sessions
• Questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator willannounce your name and affiliation to the audience andthen ask for your question.
• If other participants are asking questions, you will beplaced into a queue until you are first in line.
• While in the queue, you will be in a listen-only mode untilthe operator indicates that your phone has been activated.The operator will announce your name and affiliation andthen ask for your question.
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Introduction of Presenter
• ISA Presenter− Gerald F. Gilman, PE
− Consultant to companies for safety applications anddeveloper of training programs.
− He started consulting after 37 years at Proctor & Gamble asa Control and Information Systems Manager in the SoapSector Engineering Department.
− He was responsible for the control and information systemsat three P&G sites, the coordinator for safety instrumentedsystems and safety standards worldwide, and a keyresource for boiler control systems and boiler start-ups.
− Contact information: [email protected] or (513) 522-4154
© 2003, ISAES15w (1.0)
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Key Benefits of Seminar
• Understand control systems and instrumentation for boilers
• Understand process dynamics of a boiler and the processcontrol interactions
• Be able to describe− boiler components and their function
− how the systems interact and how to set up the controls
− swell and shrink
• Be able to configure
− Furnace draft
− Drum level feed water control
− fuel air control
− steam temperature
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Boiler Fuels
• Gas
• Oil
• Coal
• Fuel combinations
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SAMA Symbols (Scientific Apparatus Makers Association)
ENCLOSURE SYMBOLSTable 1
Function Symbol
Measuring orReadout
Manual SignalProcessing
Automatic SignalProcessing
Final Controlling
Within a circle use a letter symbol from Table IIWithin other enclosures us a symbol from Table III
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SAMA Symbols (cont’d)
MEASURING/READOUT LETTERSTable II
Process Variable FunctionA = Analysis**C = ConductivityD = DensityF = FlowL = LevelM = MoistureP = PressureS = SpeedT = TemperatureV = ViscosityW = WeightZ = Position
R = RecordingI = IndicatingT = TransmitterRT = Recording TransmitterIT = Indicating Transmitter
FRT
FR
**Self-defining symbols such as O 2, pH, etc., can be used in place of A.
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SAMA Symbols (cont’d)
SIGNAL SIGNALFUNCTION PROCESSING
SYMBOLFUNCTION PROCESSING
SYMBOL
SUMMING ∑ or + INTEGRATE OR TOTALIZE Q
AVERAGING ∑/n HIGH SELECTING
DIFFERENCE ∆ or - LOW SELECTING
PROPORTIONAL K or P HIGH LIMITING
INTEGRAL ∫ or I LOW LIMITING
DERIVATIVE d/dt or D REVERSE PROPORTIONAL -K or -PMULTIPLYING X VELOCITY LIMITING VDIVIDING ÷ BIAS ±ROOT EXTRACTION √ TIME FUNCTION f(t)EXPONENTIAL Xn VARIABLE SIGNAL
GENERATIONA
NON-LINEAR FUNCTION f(x) TRANSFER TTRI-STATE SIGNAL(RAISE, HOLD, LOWER)
b SIGNAL MONITOR H/, H/L, /L
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Simple Feedback ControlPRIMARY VARIABLE
XT
K
A T A
f(x)
SET POINTPROCESS
MANIPULATED VARIABLE
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Feedforward Plus Feedback ControlPRIMARY VARIABLE
XT
YT
SECONDARYVARIABLE
A T A
f(x)
MANIPULATED VARIABLE
PROCESS
SET POINT
K
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Cascade ControlPRIMARY VARIABLE
XT
ZT
K
K
SET POINTA AT
PROCESS
f(x)
MANIPULATED VARIABLE
SECONDARYVARIABLE
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Ratio Control
A T A
f(x)
MANIPULATED VARIABLE
K
RATIO SET
X
YT
UNCONTROLLED VARIABLE
CONTROLLEDVARIABLE
XT
PROCESS
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Audio Instructions for Q&A Sessions
• Questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator willannounce your name and affiliation to the audience and thenask for your question.
• If other participants are asking questions, you will be placedinto a queue until you are first in line.
• While in the queue, you will be in a listen-only mode until theoperator indicates that your phone has been activated. Theoperator will announce your name and affiliation and then askfor your question.
© 2003, ISAES15w (1.0)
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Live Question and Answer Session
• During Q&A, questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator will announceyour name and affiliation to the audience and then ask for yourquestion.
• If other participants are asking questions, you will be placed into aqueue until you are first in line.
• While in the queue, you will be in a listen-only mode until theoperator indicates that your phone has been activated. Theoperator will announce your name and affiliation and then ask foryour question.
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Basic Control Functions
• Regardless of thehardware and softwareused certain controlfunctions are required
• These controls are
− Furnace Draft
− Drum Level Feedwater
− Fuel Air
− Steam Temperature
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Boiler Components
COLD AIR
SUPERHEATER
DESUPERHEATER
STEAM DRUMSTEAMFROMSECONDBOILER
STEAMFROMTHIRDBOILER
STEAM TOTHE PROCESSSTEAM HEADER
COLD AIR
FEED WATER
FLUE GASES
AMBIENTAIR
F.D. FANINLETVANES
I.D. FAN INLET DAMPER
TOTALAIR
AIR HEATER
SPRAY WATER FROMFE DWATER PUMP
HOT AIRDAMPER
HOT AIR
PULVERIZEDCOAL WITHPRIMARY AIR
(P.A.)
PULVERIZED
FEEDER
P.A. CONTROLDAMPER
P.A. FAN
FROM OTHERPULVERIZERS
COLDAIRDAMPER
SECONDARYAIR
E
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Block Diagram of Boiler Control
+INPUT OUTPUT
FIRINGRATE
DEMAND
FUEL DEMAND
AIR DEMAND
FEEDWATER CONTROL
STEAM TEMPERATURECONTROL
BOILER
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Furnace Pressure Control
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System Reliability & Availability ISA-77.41
• Field transmitter device redundancy should beprovided to the extent necessary to achieve desiredsystem reliability. The following conditions apply:− When two transmitters are employed, excessive deviation
between the transmitters shall be alarmed and the associatedcontrol loop shall be transferred to manual
− When three transmitters are employed, excessive deviationbetween the transmitters shall be alarmed
• A transmitter select scheme shall be used for controlpurposes
• Furnace pressure shall be measured with threefurnace pressure transmitters, each on a separatemeasurement tap.
© 2003, ISAES15w (1.0)
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Block Diagram of Boiler Control
+INPUT OUTPUT
FIRINGRATE
DEMAND
FUEL DEMAND
AIR DEMAND
FEEDWATER CONTROL
STEAM TEMPERATURECONTROL
BOILER
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Boiler Steam Drum/Swell Shrink
STEAM
STEAM
SATURATED
WATER
WATER
FEEDWATER
WATER-MIXED STEAM BUBBLES
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Single Element Feedwater Control
SET POINTK
T
f(x)
A
A
X
LT PT
f(x)
FINAL CONTROL DEVICE
M/A CONTROL STATION
PRESSURECOMPENSATION
DRUM PRESSUREDRUM LEVEL
∫∆
Typical single-drive control system. For simplicity, redundant transmitters have not beenshown on this typical control drawing. See Figure 2A for ANSI/ISA-5.1-1984 format.
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Two Element Feedwater Control
∆∫
f(x)
K
TA
A
X X
K
LTPT PT FT TE
f(x) f(x) f(x)
FINAL CONTROL DEVICE
M/A CONTROL STATION
SET POINT
PRESSURECOMPENSATION
TEMPERATUREAND PRESSURECOMPENSATION
LEVEL
PRESSURE
STEAM
TEMPERATUREFLOWDRUM
PRESSURE
Typical single-drive control system. For simplicity, redundant transmitters have not beenshown on this typical control drawing. See Figure 3A for ANSI/ISA-5.1-1984 format.
© 2003, ISAES15w (1.0)
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Three Element Feedwater Control
PRESSURECOMPENSATION
f(x)
A
X
PT FT TE
f(x) f(x)
X
LT PT
f(x)
X
FT TE
f(x)
K
K
∆
∆
T A
FINALCONTROLDEVICE
M/A CONTROLSTATION
SET POINT
PRESSURE ANDTEMPERATURECOMPENSATION
STEAM
TEMPERATUREFLOWPRESSURE
Typical single-drive control system. For simplicity, redundanttransmitters have not been shown on this typical control drawing.See Figure 4A for ANSI/ISA-S5.1-1984 format.
LEVEL PRESSURE
DRUM
TEMPERATURECONDENSATION
FLOW TEMPERATURE
FEEDWATER
Typical single-drive control system. For simplicity, redundanttransmitters have not been shown on this typical control drawing. See
Figure 4A for ANSI/ISA-5.1-1984 format.
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Block Diagram of Boiler Control
+INPUTBOILER
OUTPUT
FEEDWATER CONTROL
STEAM TEMPERATURECONTROL
FUEL DEMAND
AIR DEMAND
FIRINGRATE
DEMAND
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Firing Single Fuel/Cross Limiting
AIR CONTROL
FT PT FT
A
A T
P I
A T
P I
A T
P I
f(x)
f(x)
Fuel FLOWSTEAM
HEADER PRESSURE AIR FLOW
SP SP
LO SELECT HI SELECTFuel CONTROL
Fuel FeedAIR DAMPER
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Dual Fuel O2 Trim
P I
TA
X
Y
X
X
C
Z YY
Y
Y
X X
Y
BSP
A X
P I
TA
X
P I
TA
X
P I
TA
X
X
P I
A T
P I
A T
A
GAS FLOW0-90,000 SCFH
FT FT
OIL FLOW0-10,000 PPH
0-30” WCFUEL
SUMMERYX
FUELCONTROL
SP
STEAM HEADERPRESSURE
PT0-850 PSI
PVSP SP
GAS CONTROL OIL CONTROL
LOW SELECT HIGH SELECT
GAS VALVE OIL VALVEFAN DAMPER
AIR CONTROL
PV
SUBMASTER
HEADERPRESSURECONTROL
AIR FLOWCHARACT...
f(x)
AIR FLOW
FT AT0-5” WC
BOILER O2
O2 10%
f(x)
O2 TRIMCONTROL
SP
STEAMFLOW
© 2003, ISAES15w (1.0)
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Audio Instructions for Q&A Sessions
• Questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator willannounce your name and affiliation to the audience andthen ask for your question.
• If other participants are asking questions, you will beplaced into a queue until you are first in line.
• While in the queue, you will be in a listen-only mode untilthe operator indicates that your phone has been activated.The operator will announce your name and affiliation andthen ask for your question.
34
Live Question and Answer Session
• During Q&A, questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator will announceyour name and affiliation to the audience and then ask for yourquestion.
• If other participants are asking questions, you will be placed into aqueue until you are first in line.
• While in the queue, you will be in a listen-only mode until theoperator indicates that your phone has been activated. Theoperator will announce your name and affiliation and then ask foryour question.
© 2003, ISAES15w (1.0)
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Excess Air vs. Boiler LoadEXCESS AIR
(% o2)
BOILER LOAD(%)
0 50 100
5
4
3
2
1
36
Non Linear Flow
0 10 20 30 40 50 60 70 80 90 100
0 1 4 9 16 25 36 49 64 81 100
Flow in %
0
10
20
30
40
50
60
70
80
90
100
0 14
916
25
36
49
64
81
100
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11
Series1
Series2
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Characterization
0 10 20 30 40 50 60 7 0 80 O U T
0 7 .5 15 22 .5 30 37 .5 45 52 .5 60 IN
0
10
20
30
40
50
60
70
80
0
7 .5
15
22 .5
30
37 .5
45
52 .5
60
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9
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Block Diagram of Boiler Control
+INPUTBOILER
OUTPUT
FIRINGRATE
DEMAND
FUEL DEMAND
AIR DEMAND
FEEDWATER CONTROL
STEAM TEMPERATURECONTROL
© 2003, ISAES15w (1.0)
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Water Side Control MechanismsDESUPERHEATER
SUPER-HEATER
SECTIONS
PURE WATER SPRAYED INTO THE SUPERHEATED STEAMVAPORIZES; DEGREE OF SUPERHEAT IS REDUCED HEAT
OF VAPORIZATION.
From Power magazine SpecialReport, “Steam Generation,”by R.J. Bender, Associate Ed.McGraw Hill, NY
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Typical Single Element Superheat Control
OPENCLOSE
K ∫
f(x)
TA
A
T T
A
A A
TT
SPRAY CONTROL VALVE SPRAY CONTROL VALVE
SPRAYINTERLOCK
SET POINT
0%
0%
100%
M / A CONTROLSTATION
FINAL STEAMTEMPERATURE
∆
© 2003, ISAES15w (1.0)
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Typical Two-Element Superheat Control
OpenClose
Final SteamTemperature
FeedforwardCalculation
f(x)
TA
T T
A
A A
Spray Control Valve Spray Block Valve
SprayInterlock
0%
0%
100%
M / A ControlStation
K
∆∫
A
TT
Setpoint
ΣLoadIndex(es)
TransientCorrection
Signal(s)
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Typical Three-Element Superheat Control
Note: 1. Attemperator Outlet Temperature or Spray Flow
OpenClose
Final SteamTemperature
TransmitterFeedback (Note 1)
FeedforwardCalculation
f(x)
TA
T T
A
A A
Spray Control Valve Spray Block Valve
SprayInterlock
0%
0%
100%
M / A ControlStation
K
K
∆
∆
∫
∫
A
TTTT/FT
Set Point
ΣLoadIndex(es)
TransientCorrection
Signal(s)
© 2003, ISAES15w (1.0)
43
Audio Instructions for Q&A Sessions
• Questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator willannounce your name and affiliation to the audience andthen ask for your question.
• If other participants are asking questions, you will beplaced into a queue until you are first in line.
• While in the queue, you will be in a listen-only mode untilthe operator indicates that your phone has been activated.The operator will announce your name and affiliation andthen ask for your question.
44
Live Question and Answer Session
• During Q&A, questions may be asked via your telephone line.
• Press the *1 key on your telephone key-pad.
• If there are no other callers on the line, the operator will announceyour name and affiliation to the audience and then ask for yourquestion.
• If other participants are asking questions, you will be placed into aqueue until you are first in line.
• While in the queue, you will be in a listen-only mode until theoperator indicates that your phone has been activated. Theoperator will announce your name and affiliation and then ask foryour question.
© 2003, ISAES15w (1.0)
45
Related Resources from ISA
• Complete, hands-on course on this topicavailable through ISA Training Institute onlineat www.isa.org/training− Boiler Control Systems Engineering (ES15)
− Burner Management Systems Engineering (ES16)
− Available any time as on-site training
• Books, software, videotapes, interactivemultimedia
• Standards, journals, membership services
Phone: (919) 549-8411E-mail Address: [email protected]
46
Additional ISA Resource Materials
• Fossil fuel power plant standards− Boiler Combustion Control ANSI/ISA-77.41-1992
− Feedwater Control System ANSI/ISA-77.42.01-1999
− Plant Demand Development ANSI/ISA-77.43-1994
− Steam Temperature Control System ANSI/ISA-77.44-1995
− Fossil Fuel Power Plant Instrument Piping InstallationANSI/ISA-77.70-1994
© 2003, ISAES15w (1.0)
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Seminar Survey
• Web-based Seminar Surveys are tools to help ISAmaintain the quality of our training programs.
• Please complete the following four slides of thesurvey and fax to ISA when it is complete.
Please fax completed survey pages to (919) 549-8288.
48
Seminar Survey (cont’d)
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Please fax completed survey pages to (919) 549-8288.
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Seminar Survey (cont’d)
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5. Demonstrated practical knowledge about the subject.6. Provided clear answers to questions/comments.
7. How many people listened at your site? 1-5 6-10 11-15 16-20 21+
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8. Would you participate in another virtual seminar? Yes No9. Did the web component add to the value of the virtual seminar? Yes No10. Did the seminar satisfy your professional objectives? Yes No
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Seminar Survey (cont’d)
Please fax completed survey pages to (919) 549-8288.
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12. List other topics you would like to view as a web seminar, along with your overall impression of the program. ________________________________________________ ________________________________________________
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Seminar Survey (cont’d)
Please fax completed survey pages to (919) 549-8288.